Earthmoving or geography altering machines such as track type tractors, motor graders, scrapers, and/or backhoe loaders, have an implement such as a dozer blade or bucket, which is used on a worksite in order to alter a geography or terrain of a section of earth. The implement may be controlled by an operator or by an autonomous grade control system to perform work on the worksite. For example, the operator may move an operator input device that controls the movement or positioning of the implement using one or more hydraulic actuators. To achieve a final surface contour or a final grade, the implement may be adjusted to various positions by the operator or the grade control system.
Positioning the implement, however, is a complex and time-consuming task that requires expert skill and diligence if the operator is controlling the movement. Conventional machines deploy proportional (P), proportional-derivative (PD), proportional-integral (PI), and/or proportional-integral-derivative (PID) controllers to attain position control of various machine implements. Such controllers may be deployed in combination with a Global Positioning System (GPS) receiver on the machine. However, since the implement is heavy and carries added weight of earth being dug as well, it becomes difficult for a control system to readily adjust the implement position and make the implement adhere to the desired control instructions. In such a case, it may be possible that the implement may not impart the desired geometry to a surface in a single pass. It may take multiple passes to get desired results which may be detrimental to overall efficiency of the operation.
For example, U.S. Pat. No. 6,615,929 describes a method and apparatus for high speed grading of a road in a single pass. A grader includes a frame supported above a surface. Two blades are pivotally fixed to the frame, and can be positioned to engage the surface. A first biasing mechanism biases the blades toward a forward position. At least one leveling board is pivotally fixed to the frame, and can be positioned to engage the surface towards rear of the blade. A second biasing mechanism biases the leveling board toward a forward position. A packing mechanism is fixed towards rear of the leveling board, and can be positioned to engage the surface. However, both the blades are of similar size and are controlled in a similar manner. Even though angle of the leveling boards can be controlled relative to the blades, it may be difficult to perform different functions with both the blades.
Thus, an improved implement system is required for efficient grading operations.